1. Field of the Invention
The present invention relates to compositions comprising antiplasticizers in combination with curable and cured organosilicon compositions, and to processes for preparing these compositions, and articles comprising these compositions.
2. Background and Relevant Information
LEIBFRIED '779, U.S. Pat. No. 4,900,779, LEIBFRIED '731, U.S. Pat. No. 4,902,731, LEIBFRIED '134, U.S. Pat. No. 5,077,134, and BARD et al. '360, U.S. Pat. No. 5,008,360, describe crosslinked organosilicon polymers and crosslinkable organosilicon prepolymers comprised of alternating polycyclic hydrocarbon residues and cyclic polysiloxanes or siloxysilane residues linked through carbon to silicon bonds; these patents are hereby incorporated by reference in their entireties. COWAN, U.S. Pat. No. 4,877,820, also hereby incorporated by reference in its entirety, discloses crosslinkable and crosslinked linear poly(organohydrosiloxane) prepolymers and polymers having at least 30% of their hydrosilation reactive .ident.SiH groups reacted with hydrocarbon residues derived from polycyclic polyenes.
Antiplasticizers are substances which, when added to polymers or other materials, produce a composition having an increased modulus. For example, Jackson, W. J., Jr. and Caldwell, J. R., "Antiplasticization. III. Characteristics and Properties of Antiplasticizable Polymers", Journal of Applied Polymer Science, Vol. 11, pp 227-244 (1967), discloses that antiplasticization is applicable to polymers which contain rigid, polar groups and stiff chains, such as many bisphenol polycarbonates and polyesters.
Furthermore, substances which act as antiplasticizers in polar polymers have been added to nonpolar polymers. For example, U.S. Pat. No. 2,590,493, to BERBERICH et al., relates to flexible siliceous sheet materials comprising an organo-polysiloxane, to which is added a liquid isometric mixture of hydrogenated terphenyls, with the objective of providing a more resilient and more elastic composition. Further, the results disclosed in Table II indicate that the addition of the hydrogenated terphenyl increases the elongation (i.e., acts as a plasticizer) of the polysiloxane.
Furthermore, U.S. Pat. No. 4,780,510, to UEMIYA, et al., relates to cross-linked optical siloxane polymers, with the disclosed objective of providing a cross-linked optical siloxane polymer having a wide variety of refractive indexes, and/or a refractive index which is easily, widely and precisely modified. UEMIYA et al discloses the addition of a group onto a polysiloxane, such as styrene, o-methylstyrene, 2-vinylnaphthalene, 9-vinylanthracene, and perfluorooctylethylene, for modifying the refractive index of the polysiloxane. UEMIYA et al. states that a cross-linked optical siloxane polymer is an attractive optical material, since it has not only good processability but also good transparency and heat resistance, and a rubbery elasticity after being cured.
A Derwent English-language abstract of Soviet Union Patent No. 1073248 discloses compounds prepared by reacting N-allylcarbazole or 9-vinylanthracene with ethylhydridedichlorosilane in a molar ratio of 1:1.2-4, in the presence of chloroplatinic acid, at 95.degree.-170.degree. C., and hydrolysis at 65.degree.-90.degree. C. in toluene or dioxan. The compounds are disclosed as finding use as active components in electrophotographic layers, and as having a high electrophotosensitivity.
Chemical Abstracts 100:35245n ("Chemical Abstracts '245") is directed to heat resistance of organosilicon resins containing siloxarophenanthrene and silofluoroene units, and refers to a U.S.S.R. document identified as Vishnovskii, F. N., et al., "Heat Resistance of Organosilicon Resins Containing Siloxarophenanthrene and silafluorene Units", Elektrotekh Prom-st., {Ser.}: Elektrotekh. Mater., (10), 3-5, 1983. This Chemical Abstract discloses increasing the heat resistance of siloxane resins by introducing phenanthrene and fluorene units into the polymer, with the highest heat resistance being obtained for siloxanes containing 60 mole percent phenanthrene units, and reports electrical properties of the modified resins comparable to those of poly(methylphenylsiloxane) MFVG-3 at 20.degree. and 180.degree., as superior to those of MFVG-3 at 220.degree.. The modified resins are disclosed as useful for impregnation of casings for electrical appliances.